Silicon carbide has excellent properties, such as a large thermal, dielectric breakdown voltage, a wide energy band gap, and a high thermal conductivity, and hence silicon carbide can be applied to a high-power power device, a high-temperature resistant semiconductor device, a radiation-resistant semiconductor device, and a high-frequency resistant semiconductor device. Since the progress in performance of silicon is reaching its margin due to the physical property limit of the material itself, silicon carbide has been attracting attention, in which it is possible to take physical property limit larger than silicon. In recent years, as energy saving technology that reduces the energy loss during power conversion to be a measure against global warming, power electronics technology using silicon carbide material has attracted the expectation. As the basic technology, the research and development of the growing technology of silicon carbide single crystal is energetically proceeded, the establishment of large diameter technology is urgently required in terms of reducing manufacturing costs for the promotion of commercialization.
As a method for growing a silicon carbide single crystal, a method using the reaction of silicon vapor with carbon to make a silicon carbide single crystal grow on the seed crystal of a silicon carbide has been known. For example, Patent Document 1 discloses a method for growing silicon carbide single crystal onto a seed crystal substrate, which comprises elevating vaporized gas from silicon material, making the gas pass through porous carbon material or through-hole perforated carbon material which is arranged above the silicon material and heated at a temperature higher than the temperature of the silicon material and the temperature of silicon carbide single crystal seed crystal substrate and 1600° C. or higher, to reach the seed crystal substrate disposed above the carbon material, thereby growing silicon carbide single crystal onto the seed crystal substrate. The method of Patent Document 1 is intended to place a carbon material having pores between the seed crystal substrate and carbon material, to use the carbon material for supplying carbon raw material for silicon carbide single crystal.
In addition, a sublimation recrystallization method is known as another growing method. In this method, a single crystal silicon carbide as a raw material is sublimated in a crystal growing vessel to recrystallize silicon carbide on a seed crystal substrate at a low temperature (for example, Patent Documents 2 and 3).
FIG. 7 shows an example of a conventional single crystal growing apparatus having a cylindrical container for producing a silicon carbide single crystal.
Hitherto, the single crystal growing apparatus 100 used in producing a single crystal silicon carbide by sublimation recrystallization method, as shown in FIG. 7, is equipped with the raw material storage unit 102 located at a lower portion of the container 101 for crystal growth, the substrate supporting part 104 supporting the seed crystal 103 with the circular substrate supporting plate arranged at above the raw material storage unit 102, and the heating device 105 arranged at outer periphery of the container 101 for crystal growth, in which a circular shielding plate 106 having a thickness of approximately 10 mm is arranged between the seed crystal 103 and the raw material storage unit 102 in order to provide temperature difference between the seed crystal 103 and the raw material storage unit 102 (for example, Patent Document 4). Since the raw material 107 in the container for crystal growth is heated from the outer peripheral side, the heated raw material has a temperature distribution in which the temperature of the outer peripheral side is higher than that of the center portion.
Therefore, in the absence the shielding plate 106, radiant heat is emitted from the raw material surface to the seed crystal directly, corresponds to the temperature distribution, whereas in the presence of the shielding plate 106, the shielding plate 106 receives the radiant heat from the raw material to be heated, and emits the radiant heat to the seed crystal or the growing crystal. Therefore, it is believed that the temperature distribution in the radial direction of the raw material is relaxed by the shielding plate 106, and then the seed crystal or the growing crystal is heated.